Prehistoric agriculture and climate change

Methane levels and the rise of (extensive) farming in Europe and Asia (The Economist)

Here’s a new article in The Economist showing evidence of climate change in the ice polars caps at the same time agrarian societies emerged.

The ice-core record shows that the level of carbon dioxide in the atmosphere made an anomalous upturn about 7,000 years ago, and that methane levels, which were also falling, began to increase about 5,000 years ago. These numbers correspond well with the rise of farming in Europe and Asia.

It appears that the extensive farming method used by early farmers was responsible of a more than proportional increase in methane, a greenhouse gas. Yet another point for Georgescu-Roegen and thermoeconomics.

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7 Responses to Prehistoric agriculture and climate change

It would be irresponsible not to consider that agriculture may be the consequence of climate change, rather the cause of such changes. Unless you’re a lobbyist, in which case you’re just looking after your own interests.

Climate is by nature inconstant. So looking at the data only for the past 8,000 years is stupid. If anything you’d want to compare levels pre agriculture (circa 20,000) and post (8,000). Remember agriculture is a new innovation, only 10,000 years old.

Cooling of the earth helped humans develop enormous brains, to cope in a difficult environment. Warming allowed them to expand and exploit the land.

There have been successive periods of cooling and warming long before primates became diurnal and sociable creates.

When will you historians realize that Homo branched out 4 MILLION YEARS AGO.

Anyway, your job is to challenge The Economist and Duke and whatever other institution.

Sarah, please refrain from using derogatory words and expressions. Saying that homos branched out 4 m years ago is totally false, they are people like you and me and their sexual orientation has nothing to do with the creation of agriculture.

On the one hand the general argument of the article makes good sense: humans’ impact on the environment did not start yesterday morning. Good. Actually any person who ever got interested in winds knows that (you have mini anticyclones over green fields and cities and mini depressions over yellow fields (just before the harvest) and above cities with white roofs.

That being said I find their evidence a bit shaky. Why 3,000BC? As Sarah pointed out agriculture started much earlier. Can a few blokes burning forests in a small part of western Europe have such an effect? Etc.

And Manuel, you should really be careful when asking a question to Sarah, she is going to eat you alive.

The article is either unbelievably dumb or misleading on purpose: the “prehistoric” human tiled the earth with wooden and corn implements, and “extensive” could have meant only a very small area, and only a very thin layer of soil. The neolithic agricultural technology was only a little better than gathering, and those people relied heavily on hunting and fishing (as proved by bones found in explored sites).

Why not blame the hunter-gatherers, since those (as proved by practices documented in even in historical times) used to start forest fires to clear the undergrowth and make place for grasses that would feed more of the herbivores they used to hunt. Those fires even protected the forest from being turned to cinder, since the undergrowth fires they started were low intensity and did not harm much the larger trees, unlike the fires that start in a “virgin” forest clogged with debris and dead undergrowth (Greece, Australia, California … hint, hint … ).

“unnatural exhalations of greenhouse gases” ? Humans are _natural_, you know … anyway, how could slash and burn agriculture release methane ??? The thought of “releasing” CO2 trapped in forest soil is also preposterous, since the layer of soil in forests is quite poor in plant nutrients of any kind, and to a “slash and burn” agriculturist was useful only because it was enriched with the ashes of the burned trees.

The picture from the article is soooo misleading … the plant being harvested looks like modern hybrid maize, judging by size … the plants cultivated 5000 years ago were not much better than the wild grasses we know now, and, judging from the tools they used, the technology outside the flood plains was to protect the desired crop from other vegetation by pulling the weeds (cutting it does not help since most wild grasses just grow back from the cut roots), and leave a few plants to drop the seed naturally, or dig small holes to place the seed, techniques that also were found in historical records (and who allow, in good years, for surprisingly large harvests, of 6 to 12 times the seed).

Herding cattle or sheep put no more pressure on the environment than having wild herbivores roam, and large scale deep plowing did not happen until iron became cheap enough to be available to those that worked the land, and that happened only in historical times: copper could not have been used for agriculture because it is very soft, bronze was extremely rare and expensive, and iron in the Iron Age was for weapons, not plows, since it was damn hard to make and while it was strong enough to cut flesh, it was not strong enough to cut earth packed with roots and stones.